Amid all the confusion, some answers are beginning to emerge

First there was the news everybody wanted to hear: a New York physician writing in Cosmopolitan reassured women that there is practically no risk of contracting AIDS through ordinary vaginal or oral sex, even with an infected man. The vaginal secretions produced during sexual arousal, he wrote, keep the virus from penetrating the vaginal walls. His explanation: "Nature has arranged this so that sex will feel good and be good for you." Then came the news nobody wanted to hear: Sex Gurus William Masters and Virginia Johnson proclaimed in their new book about AIDS that "the epidemic has clearly broken out...